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emollick's profile
Ethan Mollick
Ethan Mollick
Ethan Mollick
Verified account
@emollick

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Ethan MollickVerified account

@emollick

Professor @Wharton, studying #innovation & #entrepreneurship. Plus a professional interest in #crowdfunding, #games, ephemera, and The Future of Everything.

Philadelphia, PA
startupinnovation.org
Joined May 2009

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    Ethan Mollick‏Verified account @emollick 15 Dec 2018

    Ethan Mollick Retweeted John B. Holbein

    Wow. It turns out 3/4 of businesses p-hack themselves when they conduct A/B tests, stopping their experiments as soon as they get the results they want, resulting in wrong results the vast majority of the time. And this is likely from the most “sophisticated” companies!https://twitter.com/JohnHolbein1/status/1074091992836009984 …

    Ethan Mollick added,

    John B. Holbein @JohnHolbein1
    New: "p-Hacking & False Discovery in A/B Testing" Setup: 2,101 RCTs in which businesses track effects over time. "73% of experimenters stop experiment[s] when a[n] effect reaches 90% confidence...75% of the effects are truly null." #SocSciResearch https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3204791 … pic.twitter.com/3QoUCDp3Qp
    Show this thread
    8:41 PM - 15 Dec 2018
    • 319 Retweets
    • 832 Likes
    • Edward Schmitz Félix Balazard Andrew Garvin Tim Josie Jeffries Nukeador Rob Alexander Grokking Points Podcast Jan Mattsson
    22 replies 319 retweets 832 likes
      1. New conversation
      2. Ronny Kohavi‏ @ronnyk 16 Dec 2018
        Replying to @emollick

        Sorry, Ethan. You're misinterpreting the paper, which suffers from limited external validity. This is 3/4 of businesses that used @optimizely back in 2014, a very skewed population. Optimizely got it wrong initially, then fixed it. See https://www.amazon.com/gp/customer-reviews/R44BH2HO30T18/ref=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B00E1JO50M …

        2 replies 1 retweet 10 likes
      3. Ethan Mollick‏Verified account @emollick 16 Dec 2018
        Replying to @ronnyk @Optimizely

        Good criticism, but I don’t think its misinterpretation. You argue that Optimizely was bad about pushing people to stop tests early & experimenters have gotten better in the last few years. Those should lower prevalence (but not sure to what degree) & bad practice still a problem

        1 reply 0 retweets 0 likes
      4. Ronny Kohavi‏ @ronnyk 16 Dec 2018
        Replying to @emollick @Optimizely

        Agree that early stopping is still a problem, but not at this scale. The dataset used is from naïve experimenters who used a platform that encouraged this in 2014 (since fixed). That's like claiming that 75% of cars need tires, when the data comes from http://tirerack.com .

        0 replies 0 retweets 3 likes
      5. End of conversation
      1. New conversation
      2. Ruben Kogel‏ @chilicondata 16 Dec 2018
        Replying to @emollick @Noahpinion

        yea it's called peeking and it's a well known problem in A/B experimentation and one that data science teams are keenly aware of. the data for this paper dates back to 2014 and comes from a platform that makes A/B test accessible to non-technical folks - i.e. not data scientists

        2 replies 1 retweet 5 likes
      3. Ethan Mollick‏Verified account @emollick 16 Dec 2018
        Replying to @chilicondata @Noahpinion

        Yes, fair criticism as to the extent of the problem, might be much less (given timeframe and platform) but might be more (many more people testing, much of it even less sophisticated). More research needed!

        1 reply 0 retweets 0 likes
      4. Ruben Kogel‏ @chilicondata 16 Dec 2018
        Replying to @emollick @Noahpinion

        absolutely. more research and more attention needed, particularly in business schools where those questions are largely ignored rn. also anyone doing research on the topic should *talk to practitioners*. otherwise it feels disconnected to reality.

        1 reply 0 retweets 1 like
      5. Ruben Kogel‏ @chilicondata 16 Dec 2018
        Replying to @chilicondata @emollick @Noahpinion

        (full disclosure: I went to Booth 2012-2014 and took every stats class and never once heard this topic being discussed)

        0 replies 0 retweets 0 likes
      6. End of conversation
      1. wmdailey‏ @wmdailey 16 Dec 2018
        Replying to @emollick @Noahpinion

        This is what happens when you slash R&D but still make wild promises to shareholders and the public regarding innovation.

        0 replies 0 retweets 12 likes
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      1. New conversation
      2. Ronny Kohavi‏ @ronnyk 16 Dec 2018
        Replying to @emollick

        Claim of widespread p-hacking were sensationalized in the paper, which is suffering lack of external validity on two axes: skew due to massive selection bias and time bias. Seehttps://www.linkedin.com/pulse/p-hacking-ab-testing-sensationalized-ronny-kohavi/ …

        1 reply 6 retweets 5 likes
      3. au jus soli‏ @rone 18 Dec 2018
        Replying to @ronnyk @emollick

        are you saying they p-hacked the p-hack paper?

        1 reply 0 retweets 0 likes
      4. Ronny Kohavi‏ @ronnyk 18 Dec 2018
        Replying to @rone @emollick

        Ronny Kohavi Retweeted Dean Eckles

        That's an orthogonal claim that others made: a p-value of 0.03 is the lowest in the table of multiple tests:https://twitter.com/deaneckles/status/1074845375096336385 …

        Ronny Kohavi added,

        Dean Eckles @deaneckles
        Replying to @thosjleeper
        Though that highlights the multiple testing that makes p = .03 even less weighty.
        1 reply 0 retweets 0 likes
      5. au jus soli‏ @rone 18 Dec 2018
        Replying to @ronnyk @emollick

        aw man i was just making a joke

        0 replies 0 retweets 1 like
      6. End of conversation
      1. Clayton Bellamy‏ @claybell1973 16 Dec 2018
        Replying to @emollick @Noahpinion

        This surprises no one who has been doing analytics in a commercial setting

        0 replies 0 retweets 7 likes
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      1. New conversation
      2. Doctor Ben‏ @ben_spigel 16 Dec 2018
        Replying to @emollick

        I’m starting to remodel my entrepreneurship classes to help students build the humility to accept that their initial assumptions were wrong.

        3 replies 0 retweets 10 likes
      3. Kevin Walsh‏ @kdwalsh 17 Dec 2018
        Replying to @ben_spigel @emollick

        How?

        1 reply 0 retweets 0 likes
      4. Doctor Ben‏ @ben_spigel 17 Dec 2018
        Replying to @kdwalsh @emollick

        That’s the hard part. Right now working on them setting up and running market experiments with pre-defined success thresholds

        0 replies 0 retweets 2 likes
      5. End of conversation
      1. Cat-Thu Nguyen Huu‏ @catthu 16 Dec 2018
        Replying to @emollick @ViliLe

        Sadly, this does not surprise me in the slightest.

        0 replies 0 retweets 6 likes
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      1. Josh Garofalo‏ @swaycopy 18 Dec 2018
        Replying to @emollick

        Not surprising. Even among SaaS companies, testing cultures are rare. Part of it is ignorance (not understanding why a test must be statistically significant). But a larger portion is that running a test that doesn't go as planned is seen as a bad thing.

        0 replies 0 retweets 2 likes
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      1. Alex Salkever‏ @AlexSalkever 16 Dec 2018
        Replying to @emollick

        Is there a compendium somewhere of bogus marketing and growth hacking tactics that look statistically relevant but in fact are worthless?

        0 replies 0 retweets 2 likes
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      1. Miquel Llobet‏ @mllobet 16 Dec 2018
        Replying to @emollick

        cc: @DrDavidPier

        0 replies 0 retweets 1 like
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